Why Windows Vista is disk space hog? explains Microsoft

Windows Vista was always cataloged as a resource hog OS. Beyond being CPU- and RAM-hungry, Vista also managed to grab an unprecedented part of the hard drive, requiring for the high-end versions a 40GB HDD, with at least 15 GB of available space just to install. Furthermore, even a clean install of Windows Vista takes full […]

Windows Vista was always cataloged as a resource hog OS. Beyond being CPU- and RAM-hungry, Vista also managed to grab an unprecedented part of the hard drive, requiring for the high-end versions a 40GB HDD, with at least 15 GB of available space just to install. Furthermore, even a clean install of Windows Vista takes full advantage of all those free 15 GB of disk space.

“As we all know, adding new functionality consumes additional disk space--in Windows or any software. In reality, 'code' takes up a relatively small percentage of the overall Windows footprint. The actual code required for a Windows Vista Ultimate install is just over 2GB, with the rest of the footprint going to 'data' broadly defined,” revealed Michael Beck, a program manager in the core OS deployment feature team.

In fact, the vast majority of the disk space is consumed by features that have been added in the evolution from Windows XP to Windows Vista. Beck indicated that features such as system recovery, performance, data protection, and troubleshooting were largely responsible for Vista's insatiable hunger for free disk space. 

“Some of these include system restore, hibernation, page file, registry back up, and logging. Each of these represent 'backup state' that is available to the system to recover from any number of situations, some planned and others not,” Beck stated.

Source:→ Softpedia